In the field of image reproducing systems such as a color scanner, a layout scanner system exists which has a function of recording the images of plural original pictures on a photosensitive film in a desired layout pattern. However, if a a pictorial component having various halftone dot density gradations and a letter or drawing (called a "literal" hereinafter) component having a binary level (black or white) must be recorded together in a desired layout pattern on a photosensitive film, higher resolving power is required for recording the pixels of the literal component in comparison with that for recording the pixels of the pictorial component, because the literal component consists mainly of fine line segments. Thus, if both components are recorded with an identical resolving power suitable for recording the literal component, excessive processing time is needed.
In addition, when a disc memory is used for performing layout work, the memory is required to have greater amount of capacity, which causes longer processing time. In order to resolve the above problem, U.S. application Ser. No. 471,859, now U.S. Pat. No. 4,553,172, discloses a method wherein first image data of pictorial components and that of literal components scanned more minutely are together input to one memory according to a desired layout pattern, wherein both data are separable. The image data are then output from the memory separately to be used for recording respective reproduction images on a photosensitive film.
However in this method, as the border pixels between both components can only be recorded by the image data of either the pictorial component or the literal component, there exists a drawback that a vacant (white) portion might be produced along the border.
In order to overcome the above drawback, U.S. application Ser. No. 507,719 discloses a method in which the border pixels between a literal component P.sub.L and a pictorial component P.sub.P are recorded using the image data of both components simultaneously as shown in FIG. 1. To prevent any blank areas along contours of the line drawing in the reproduction from occurring, graphic signals originating from pictorial element of a line drawing are added to a line signal originating from the pictorial element. This method is also permissible when the literal pixel is recorded in 100% halftone dot density, but produces an unwelcome solid portion P.sub.5 on the border pixels when the literal component is recorded in less than 100% halftone dot density as shown in FIG. 1.
On the other hand, U.S. application Ser. No. 532,737 discloses a method in which the border pixels are recorded by converting picture and line signals into different digital words having the same number of bits and adding bits to distinguish between line and picture signals. A dot is formed in the picture portion according to picture information. In the line drawing, a screen tint is formed according to dot percentage data, and in the boundary portion line drawing data rather than picture data are output. However in this method, because the border pixels are not recorded by using the pictorial component data, a vacant portion P.sub.P0 is produced on the border pixels as shown in FIG. 2. Even this method, however, cannot resolve the conventional problems.
Furthermore, conventional methods have a common drawback of the appearance of vacant portions owing to incorrect registration, which also affects the quality of reproduced images.